Fix exception chaining in test/ (pytorch#44193)

Summary:
## Motivation
This PR fixes pytorch#43770 and is the continuation of pytorch#43836.

## Description of the change
This PR fixes exception chaining only in files under `test/` where appropriate.
To fix exception chaining, I used either:
1. `raise new_exception from old_exception` where `new_exception` itself seems not descriptive enough to debug or `old_exception` delivers valuable information.
2. `raise new_exception from None` where raising both of `new_exception` and `old_exception` seems a bit noisy and redundant.

## List of lines containing `raise` in `except` clause:
I wrote [this simple script](https://gist.github.com/akihironitta/4223c1b32404b36c1b349d70c4c93b4d) using [ast](https://docs.python.org/3.8/library/ast.html#module-ast) to list lines where `raise`ing in `except` clause.

- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_cpp_extensions_aot.py#L16
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_jit.py#L2503
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/onnx/model_defs/word_language_model.py#L22
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/onnx/verify.py#L73
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/onnx/verify.py#L110
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/onnx/test_verify.py#L31
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/distributed/test_c10d.py#L255
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/distributed/test_c10d.py#L2992
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/distributed/test_c10d.py#L3025
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/distributed/test_c10d.py#L3712
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/distributed/test_distributed.py#L3180
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/distributed/test_distributed.py#L3198
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/distributed/test_data_parallel.py#L752
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/distributed/test_data_parallel.py#L776
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_type_hints.py#L151
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_jit_fuser.py#L771
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_jit_fuser.py#L773
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_dispatch.py#L105
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_distributions.py#L4738
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_nn.py#L9824
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_namedtensor.py#L843
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_jit_fuser_te.py#L875
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_jit_fuser_te.py#L877
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_dataloader.py#L31
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_dataloader.py#L43
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_dataloader.py#L365
- [x] https://github.com/pytorch/pytorch/blob/f8f35fddd4b2bd788953d6d6ccfadf690b73a3e8/test/test_dataloader.py#L391

Pull Request resolved: pytorch#44193

Reviewed By: albanD

Differential Revision: D23681529

Pulled By: malfet

fbshipit-source-id: 7c2256ff17334625081137b35baeb816c1e53e0b

Author: akihironitta

test/onnx/model_defs/word_language_model.py

@@ -20,7 +20,7 @@ def __init__(self, rnn_type, ntoken, ninp, nhid, nlayers,
                 nonlinearity = {'RNN_TANH': 'tanh', 'RNN_RELU': 'relu'}[rnn_type]
             except KeyError:
                 raise ValueError("""An invalid option for `--model` was supplied,
-                                 options are ['LSTM', 'GRU', 'RNN_TANH' or 'RNN_RELU']""")
+                                 options are ['LSTM', 'GRU', 'RNN_TANH' or 'RNN_RELU']""") from None
             self.rnn = nn.RNN(ninp, nhid, nlayers, nonlinearity=nonlinearity, dropout=dropout)
         self.decoder = nn.Linear(nhid, ntoken)
 

test/test_cpp_extensions_aot.py

@@ -12,11 +12,11 @@
     import torch_test_cpp_extension.cpp as cpp_extension
     import torch_test_cpp_extension.msnpu as msnpu_extension
     import torch_test_cpp_extension.rng as rng_extension
-except ImportError:
+except ImportError as e:
     raise RuntimeError(
         "test_cpp_extensions_aot.py cannot be invoked directly. Run "
         "`python run_test.py -i test_cpp_extensions_aot_ninja` instead."
-    )
+    ) from e
 
 
 class TestCppExtensionAOT(common.TestCase):

test/test_dataloader.py

@@ -28,7 +28,7 @@
     err_msg = ("psutil not found. Some critical data loader tests relying on it "
                "(e.g., TestDataLoader.test_proper_exit) will not run.")
     if IS_PYTORCH_CI:
-        raise ImportError(err_msg)
+        raise ImportError(err_msg) from None
     else:
         warnings.warn(err_msg)
 
@@ -40,7 +40,7 @@
     err_msg = ("faulthandler not found. Some data loader tests use it for error "
                "reporting (e.g., TestDataLoader.test_proper_exit).")
     if IS_PYTORCH_CI:
-        raise ImportError(err_msg)
+        raise ImportError(err_msg) from None
     else:
         warnings.warn(err_msg)
 

test/test_distributions.py

@@ -4733,9 +4733,9 @@ def test_invalid(self):
                 try:
                     with self.assertRaises(ValueError):
                         Dist(validate_args=True, **param)
-                except AssertionError:
+                except AssertionError as e:
                     fail_string = 'ValueError not raised for {} example {}/{}'
-                    raise AssertionError(fail_string.format(Dist.__name__, i + 1, len(params)))
+                    raise AssertionError(fail_string.format(Dist.__name__, i + 1, len(params))) from e
 
     def tearDown(self):
         super(TestValidation, self).tearDown()

test/test_jit.py

@@ -2526,7 +2526,7 @@ def test_pytorch_jit_env_off(self):
         try:
             subprocess.check_output([sys.executable, '-c', 'import torch'], env=env)
         except subprocess.CalledProcessError as e:
-            raise RuntimeError("Could not 'import torch' with PYTORCH_JIT=0")
+            raise RuntimeError("Could not 'import torch' with PYTORCH_JIT=0") from e
 
     def test_print_op_module(self):
         # Issue #19351: python2 and python3 go through different paths.

test/test_jit_fuser.py

@@ -768,7 +768,7 @@ def test_lstm_traced_cpu(self):
                 warnings.warn('CPU fuser test has failed! This is not a hard failure, '
                               'because the kernels sometimes trigger bugs in compilers '
                               '(most notably GCC 7.2).')
-                raise unittest.SkipTest('Failed to compile')
+                raise unittest.SkipTest('Failed to compile') from e
             else:
                 raise
 

test/test_jit_fuser_te.py

@@ -889,7 +889,7 @@ def test_lstm_traced_cpu(self):
                 warnings.warn('CPU fuser test has failed! This is not a hard failure, '
                               'because the kernels sometimes trigger bugs in compilers '
                               '(most notably GCC 7.2).')
-                raise unittest.SkipTest('Failed to compile')
+                raise unittest.SkipTest('Failed to compile') from e
             else:
                 raise
 

test/test_namedtensor.py

@@ -840,7 +840,7 @@ def _test(testcase, names=('N', 'D'), device='cpu'):
                 out = testcase.lambd(tensor)
             except RuntimeError as err:
                 # Get a better error message by catching the error and asserting.
-                raise RuntimeError('{}: {}'.format(testcase.name, err))
+                raise RuntimeError('{}: {}'.format(testcase.name, err)) from err
             self.assertEqual(out.names, tensor.names,
                              msg=testcase.name)
 

test/test_type_hints.py

@@ -148,7 +148,7 @@ def test_doc_examples(self):
                     target_is_directory=True
                 )
             except OSError:
-                raise unittest.SkipTest('cannot symlink')
+                raise unittest.SkipTest('cannot symlink') from None
             (stdout, stderr, result) = mypy.api.run([
                 '--follow-imports', 'silent',
                 '--check-untyped-defs',